The increasing use of wireless telephones and personal computers by the general population has led to a corresponding demand for advanced telecommunication services that were once thought to only be meant for use in specialized applications.
For example, in the late 1980""s, wireless voice communication such as available with cellular telephony had been the exclusive province of the businessman because of expected high subscriber costs. The same was also true for access to remotely distributed computer networks, whereby until very recently, only business people and large institutions could afford the necessary computers and wireline access equipment.
However, the general population now increasingly wishes to not only have access to networks such as the Internet and private intranets, but also to access such networks in a wireless fashion as well. This is particularly of concern for the users of portable computers, laptop computers, hand-held personal digital assistants and the like who would prefer to access such networks without being tethered to a telephone line.
There still is no widely available satisfactory solution for providing low cost, high speed access to the Internet and other networks using existing wireless networks. This situation is most likely an artifact of several unfortunate circumstances. For example, the typical manner of providing high speed data service in the business environment over the wireline network is not readily adaptable to the voice grade service available in most homes or offices. In addition, such standard high speed data services do not lend themselves well to efficient transmission over standard cellular wireless handsets.
Furthermore, the existing cellular network was originally designed only to deliver voice services. At present, the wireless modulation schemes in use continue their focus on delivering voice information with maximum data rates only in the range of 9.6 kbps being readily available. This is because the cellular switching network in most countries, including the United States, uses analog voice channels having a bandwidth from about 300 to 3600 Hertz. Such a low frequency channel does not lend itself directly to transmitting data at rates of 28.8 kilobits per second (kbps) or even the 56.6 kbps that is now commonly available using inexpensive wire line modems, and which rates are now thought to be the minimum acceptable data rates for Internet access.
Switching networks with higher speed building blocks are just now coming into use in the United States. Although certain wireline networks, called Integrated Services Digital Networks (ISDN), capable of higher speed data access have been known for a number of years, their costs have only been recently reduced to the point where they are attractive to the residential customer, even for wireline service. Although such networks were known at the time that cellular systems were originally deployed, for the most part, there is no provision for providing ISDN-grade data services over cellular network topologies.
ISDN is an inherently circuit switched protocol, and was, therefore, designed to continuously send bits in order to maintain synchronization from end node to end node to maintain a connection. Unfortunately, in wireless environments, access to channels is expensive and there is competition for them; the nature of the medium is such that they are expected to be shared. This is dissimilar to the usual wireline ISDN environment in which channels are not intended to be shared by definition.
The present invention provides high speed data and voice service over standard wireless connections via an unique integration of ISDN protocols and existing cellular signaling such as is available with Code Division Multiple Access (CDMA) type modulated systems. The present invention achieves high data rates through more efficient allocation of access to the CDMA wireless channels. In particular, a number of subchannels are defined within a standard CDMA channel bandwidth, which is normally necessary to support the ISDN protocol, such as by assigning different codes to each subchannel. The instantaneous bandwidth needs of each on-line subscriber unit are met by dynamically allocating multiple subchannels of the RF carrier on an as needed basis for each session. For example, multiple subchannels are granted during times when the subscriber bandwidth requirements are relatively high, such as when downloading Web pages and released during times when the line content is relatively light, such as when the subscriber is reading a Web page which has been previously downloaded or is performing other tasks.
Subchannel assignment algorithms may be implemented to offer various levels of priority service to particular subscribers. These may be assigned based upon available ports per subscriber, expected user bandwidth, service premium payments, and so on.
In accordance with another aspect of the invention, some portion of the available bandwidth is initially allocated to establish a communication session. Once the session has been established, if a subscriber unit has no data to present for transmission, namely, if the data path remains quiescent for some period of time, the previously assigned bandwidth is deallocated. In addition, it is preferable that not all of the previously assigned bandwidth be deallocated, but rather at least some portion be kept available for use by an in-session subscriber. If the inactivity continues for a further period of time, then even the remaining portion of the bandwidth can be deallocated from the session. A logical session connection at a network layer protocol is still maintained even if no subchannels are assigned.
In a preferred arrangement, a single subchannel is maintained for a predetermined minimum idle time for each network layer connection. This assists with more efficient management of channel setup and tear down.